In wireless systems, power efficiency of a power amplifier may be important. This may especially apply in an average power operating mode in systems with modulation such as orthogonal frequency-division multiplexing (OFDM). Digital power amplifiers (DPA) may enable to provide efficient power amplification and to replace further components provideng needed functions in a transmitter, e.g. digital to analog converter (DAC), filter, or mixer. For example, in mm-wave beamforming systems a digital power amplifier might replace phase shifters and power splitters.
Digital power amplifiers may show reduced efficiency at 6 dB back-off operating point. The circuit design of circuits used to implement the digital power amplifier may be a key driver for improving power efficiency. Other concepts may provide back-off enhancement to improve efficiency at the 6 dB back-off operating point. However, an effectiveness of achieved back-off enhancement may be low. There may be a desire to improve an efficiency of a digital power amplifier.